This invention relates to asymmetric synthesis. Asymmetric synthesis is of general interest, often in the pharmaceutical industry, since frequently only one optically active isomer (enantiomer) is therapeutically active. Thus, in many processes, some of which include hydrogenation, olefin isomerization, hydrocarbonylation, hydrocyanation, oxidation, cyclooligomerization and hydroformylation, it is desirable to induce formation of one particular enantiomer over its mirror image. Currently, asymmetric induction can be carried out with organometallic catalysts having optically active ligands such as PR'R"R'" in (PPh.sub.3).sub.2 Rh(PR'R"R'")Cl. Seldom is the asymmetric induction ever near 100% effective, however, in part because the substrate molecule can take more than one directional approach in attacking the metallic center of the catalyst molecule.
There is therefore a real and continuing need to provide catalysts which will allow more efficient asymmetric induction to yield the desired enantiomer. This invention has as its primary objective the fulfillment of this need.
Another objective of the present invention is to provide chiral catalysts of quadruped ligands which are highly effective in induction of chirality in substrate molecules.
Yet another objective of the present invention is to prepare chiral catalysts of triped ligands which are highly effective in induction of chirality into substrate molecules.
A further objective of the present invention is to provide a method of inducing organic synthesis reactions to produce high yields of desired chiral molecules by employing organometallic catalysts containing chiral ligands which establish a single rigid enantio-face near the catalyst site, thus preventing multiple approaches of the substrate molecule to the catalytic complex, and thereby inducing chirality.
The method and manner of accomplishing each of the above objectives will become apparent from the detailed description of the invention which follows.